Tire tread



Dec. 29, 1936. H w so 2,065,697

TIRE TREAD Filed Feb. 20, 195

/ INVENTOR Paul E. wkl luoq I I 7 5 5 111;? Orn9:

that-by providing the tread with pockets closed side and end closingwalls of the pockets flare 20 55 canized thereto, is indicated by thenumeral e. been formed and cured. In practice it has been 56 PatentedDec. 29, 1936' I 2,965,697

UNITED STATES FATENT @FFWE TIRE TREAD Paul E. Hawkinson, Minneanolis,Minn. Application February 20, 1936, Seriai No. 64,968

1 fliaimt (QB. 152-.14)

My invention relates to pneumatic tires and The substantially integralline on which the particularly to "the treads thereof and has for itsretread joins the tire'casing is marked by dotted object to provide atread that will run smoothly line i. The retread is formed with pockets8 upon'concrete and likeroad beds and which will and at its sides withoutwardly projecting shoulhave extremely high -traction for running inders 9. These pockets 8, as above indicatedfare snow, thereby makingunnecessary the use of closed at their sides and inner and outer ends.chains and like auxiliary traction tire attach- Said pockets areobliquely set so as to prevent merits. skidding aswell as to givedriving traction, and

To the above ends, I provide a tire tread that they are preferablyalternated or set zigzag cir- 10 has a continuous running surface brokenonly cumferentially but are spaced apartsoas to leave 10 by pockets ofnovel construction and arrangesmooth continuous tread surface it that isnot ment, which pockets, nevertheless, leave a concompletely broken atany place and is continutinuous intervening tread surface. ous betweenthe pockets, thereby giving a smooth Tire treads having deep transversecircumrunning surface for travel on concrete or other s ferentiallyalternated grooves. open at outer ends, smooth road beds.

have hitherto been made and used; but from such The pockets may beformed in any new tires open grooves snow caught will escape and not orin the retreads of retreadecl tires and in the iorrn the most highlyerhcient nor compact snow latter instance, the pockets will be formedenridges necessary for the best traction I found tirely within theretreaci. As will be noted, the

at sides and ends, so that the compressed snow outward so that theycatch the snow and comcan not escape therefrom, the tire in runningpress the same into the ridges, but will clear the through snow willpress and leave on the road formed snow ridges under movement of thetire. or line or travel very solid tooth-like ridges. In This clearingaction is important because it prefact, in practice it has been foundthat the tooth-' vents distorting or breaking loose of the snow 25 likeridges formed by the pockets will become so ridges after they have oncebeen compressed and hard andflrmly anchored that very considerableformed and securely anchored to the road bed. force is required todislodge or loosen the same. in actual practice, tire retrea-ds formedwith The tire thus lays a toothed or sort of a rackedthe pocketsdesigned as described have been like track on which the tire tread runsmuch like found to be very highiy efiicient and, in fact; to 30 therunning of a gear in a toothed rack. Also, give better traction to thetire than can be obthe pockets are so formed that they will clear tamedby tread chains or like auxiliary attachthemselves of the formed snowribs formed ments. The tread chains are not only expensive therebywithout distorting or breaking the same. and wear rapidly, especially onconcrete roads,

as A preferred form of the tire is-illustrated in but are objectionablebecause of the noise and the accompanying drawing wherein likecharjolting and jarring actions and the trouble in acters indicate likeparts throughout the several applying and removing the-same. Thisimproved views. 1 tire trend has all oi the advantages of the tireReferring to the drawing: chain without any of the disadvantages or 011-Fig. 1 is a fragmentary plan view looking at jections thereto. Moreover,this tire tread is no 40 the'iace oi the tread of a tire casingembodying more expensive to apply than any other tire tread theinvention; involving the same amount and grade of rubber.

Fig. 2 is a section taken through an upper In iact,it is a good andsatisfactory tire for the portion oi the tire on the irregular line 2-42or smooth roads and a most highly desirable tire for Fig. 1, some partsbeing broken away; travelling through snow. 45

Fig. 3 is a transverse section, with some parts its a furtherimprovement in the construction broken away. taken through theroad-engaging and operation of the tread, the tread rubber is portion ofthe tire and showing the flattened cured circumferentially short and inflattened coruiitimi thereof at the point of road contact; c ndi i nSubstantially as h wn in Fi so d Whether the tire be new, in whichinstance the Fig. 4 is a fragmentary section taken on the ori inal t eais to b ap or w ether the line 4-5 of Fig. 1. tire be a worn one, inwhich case a retread is to The tire casing proper is indicated by the beapplied, the tread rubber when cured short" numeral 6 and a retread,which has been vul m t be np after h body oi'the casing has flow ofrubber just ahead of that portion which contacts the road. This isusually designated 1 as a tread wave and produces increased heat andfriction in the rubber and tends to impede I the forward movement of thetire.

The just above noted efiects may be overcome and the improv'ement in theaction of the tread or retread improved by applying and curing the treadrubber short. Broadly, this curing of the tread rubber short isdisclosed and broadly claimed in my prior patents.Nos. 1,917,261 and1,917,262 of date July'll, 1933. As disclosed in my said prior patentsthe tire casing can be circumferentially contracted by spreading thecasing laterally; and the application of the rubber short" under normalstress may be accomplished by applying and vulcanizing the tread rubberunder normal stress while the casing is thus contracted and laterallyspread so that the tread rubber transversely is cured fiat or in thecondition to whlchit will be subjected by road contact under load. Withthe rubber cured short the tread wave is avoided and the friction andgeneration of heat, hitherto produced by "tread waves is eliminated.

The tread rubber cured short has a special relation to or action uponthe closed pockets of this improved tire. When the tire is at fulldiameter, the tread rubber, which has been cured short", will bestretched and the pockets will be relatively wide spread. When the treadrubber, under load, is pressed and flattened upon the road, there willbe a slight contraction or the pockets at the very time that they arecompressing the snow, for example, into the toothlike ridges. As thetread rubber leaves the formed ridges, it will assume a stretchedcondition which tends to spread or expand the pockets and thus greatlyassist in releasing the hard compressed ridges anchored to the road-bed.In

a tire constructed as just above discussed, the curing radius and theloaded rolling radius will be substantially the same.

What I claim is:

' A tire casing having a rubber tread surface terminating in abrupt sideshoulders on the tread surface of the casing, said tread havingobliquely disposed pockets in staggered arrangement, the

inner extremities of said pockets terminating approximately at themedial plane of the casing, and the outer ends of said pocketsterminating in walls extended approximately to and parallel with .saidside shoulders, the tread face of the tire having a continuous treadsurface between the said pockets, and the walls of said pockets beingoblique so that they are self-clearing of compressed snow.

PAUL E. HAWKINSON.

